This invention relates to flow control and more particularly, to the control of fluid flow with respect to the infusion and aspiration of fluids in venous and arterial systems.
A common container for medical fluids is a plastic pouch which contains saline, i.e. a salt solution used in biological and physiological processes. The contents of such a container are carried by a conduit, typically plastic tubing, through a valve that is used to prevent backflow.
In addition, other valves can be used with the conduit to provide for the infusion and/or aspiration of other substances, such as medicaments, body fluids, and anesthetics. Infusion is commonly used to introduce saline or other medical fluids into veins, while aspiration is commonly used to draw fluids from body cavities.
The ordinary valve used with conduits from medicinal containers functions by the deflection of an elastomeric element towards and away from a valve seat. The deflection is towards the valve seat in order to prevent flow, and away from the seat to permit flow.
In some cases the control of fluid flow is with respect to a multiplicity of channels that have varying degrees of convergence with one another. A typical multichannel arrangement makes use of connectors which permit the intercoupling of flow channels. For example, when two channels are to be joined to permit a common output, the connector can take the form of a fitting that resembles a "Y". When one of the channels terminates in an infusion site, the prior practice has been to access the site by needles, which are undesirable.
Because of the desirability of achieving needleless injection and infusion of fluids, there have been numerous attempts to achieve a satisfactory device. One such effort is disclosed in Rogers et al. U.S. Pat. No. 5,006,114 of Apr. 9, 1991 in which a valve assembly has a Luer lock on an inlet, and a movable piston seals the inlet.
When a syringe is attached to the Rogers inlet the piston is displaced to unseal a fluid channel which connects the end of the syringe to an outlet, and then to a device connected to a patient. When the syringe is removed from the inlet the piston is moved to its original closed position by an internal spring. This device suffers from the disadvantage that the spring acting against the piston results in a force against the inserted Luer tip that increases as the piston is displaced.
In addition, the Rogers valve assembly provides an outlet channel at an angle in relation to the inlet. As a consequence, it is difficult to manufacture the device, and there is a tendency for flash to accumulate at the entrance of the outlet channel in the vicinity of the piston.
Moreover, the Rogers design is intended for a Luer fitting which does not have a taper so that when the conventional tapered Luer fitting is employed, it can become jammed in the straight line walls of the inlet.
An attempt to overcome the disadvantages of Rogers is disclosed in Raines, U.S. Pat. No. 5,147,333, which issued Sep. 15, 1992. Raines accommodates a tapered Luer, but there is the continued disadvantage of the need for a spring to urge a piston or spool forwardly during closure of the valve and rearwardly when the valve is being opened.
As a result, the disadvantageous increase in spring force with displacement continues to be present. Furthermore, Raines has a "backcheck" valve which requires a pair of vertically offset ports that extend laterally from a tubular body, and a spool or piston is disposed between the ports. In addition, like the Rogers' predecessor, the piston or spool in Raines requires at least one projection from the end of the piston contacted by a Luer tip in order to permit the flow of fluid from the tip through the valve.
Furthermore, like Rogers, Raines is subject to difficulties in manufacture because of flash since the various outlet ports are angularly, i.e., perpendicularly, oriented in relation to their inlets.
Other techniques for the needleless infusion and aspiration of fluids are disclosed in my co-pending application Ser. No. 08/135,673, filed Oct. 13, 1993, now U.S. Pat. No. 5,509,433, issued Apr. 23, 1996, as well as in my other pending applications which are continuations-in-part of Ser. No. 08/135,673.
Accordingly, it is an object of the invention to achieve enhanced needleless injection, infusion and aspiration. A related object of the invention is to overcome disadvantages of the prior art.
A further object of the invention to enhance the control that can be achieved over fluid flow. A related object is to enhance flow control where fluid infusion or combination is to take place.
An important object of the invention is to eliminate the need for needle usage at injection sites. A related object is to maintain sterility at injection sites that are operated without needles.
An additional object of the invention is to improve the performance of valves for infusion, injection, aspiration and control of fluid flow.
A still further object of the invention is to achieve improved sealing pressure on components used in the infusion and aspiration of medicinal fluids.